Field of the Invention
The present invention relates to a mechanism for switching driving force in an image-forming apparatus.
Description of the Related Art
An image-forming apparatus in which a plurality of rotating members is rotationally driven by unidirectional rotational driving force can be equipped with a driving force transmission device that can switch the rotation direction of some rotating members to a reverse direction. The conventional driving force transmission device uses a planetary gear mechanism (Japanese Patent Application Publication No. 2011-140980). The planetary gear mechanism is constituted by three rotating elements, namely, a sun gear, an inner-tooth gear, and a planetary gear carrier, and the rotation direction on the output side can be switched (changed) by distributing the drive input, drive output, and rotation stop between the elements. In the structure disclosed in Japanese Patent Application Publication No. 2011-140980, a drive switching member interlocked with a solenoid is provided between two planetary gear mechanism arranged on the same plane, the drive switching member is engaged with the sun gear of one of the planetary gear mechanism, and a drive transmission path is selected by stopping the rotation thereof. In other words, by selecting a sun gear that actuates and stops the solenoid, it is possible to switch the rotation direction on the output side while the rotation direction on the input side (drive source) remains the same.
However, there is still room for improvement in terms of miniaturization, noise reduction, and other problems in the driving force transmission device disclosed in Japanese Patent Application Publication No. 2011-140980 in which the rotation direction on the output side is switched while the rotation direction on the input side (drive source) remains the same.